A storage area network (SAN) may be implemented as a high-speed, special purpose network that interconnects different kinds of data storage devices with associated data servers on behalf of a large network of users. Typically, a storage area network includes high-performance switches as part of the overall network of computing resources for an enterprise. The storage area network is usually clustered in close geographical proximity to other computing resources, such as mainframe computers, but may also extend to remote locations for backup and archival storage using wide area network carrier technologies. Fibre Channel networking is typically used in SANs although other communications technologies may also be employed, including Ethernet and IP-based storage networking standards (e.g., iSCSI, FCIP (Fibre Channel over IP), etc.).
In one configuration, switches are assembled in a chassis using a selection of blade components of a SAN switch. Individual blade components are fitted into slots in the chassis and connected to a chassis backplane for interconnectivity. For example, line card blades, switch blades, and other blade components can be inserted into a chassis to provide a scalable and customizable storage network switch configuration. Typically, the blades are controlled by shared control processors (e.g., one active and one backup), powered by one or more shared power supplies through the backplane, and cooled by a shared set of cooling fan trays.
Fabric-based intelligent services, such as routing, virtualization, and distance services, may be added to a switch to enhance the performance, scalability, and features of the switch. For example, a wide area connectivity service blade can be inserted into an open slot in the chassis to provide fibre channel over IP bridging. In this fashion, the intelligent services can be managed as part of the switch.
However, adding such services as blades in a chassis presents significant limitations. A chassis has a limited number of slots, and a SAN administrator may not have an open slot in which to add an intelligent service blade. Even with an available slot, a service blade adds additional risk to the core switch, reducing the overall mean-time-between-failures (MTBF). Further, intelligent service blades tend to run hotter than core switch blades and therefore require placement in the better-cooled slots in the chassis. If such slots are already occupied by other blades, addition of a service blade can disrupt service as the other blades are moved around in the chassis. A chassis backplane also has power and signaling constraints that can restrict the scalability of a switch, particularly when an intelligent services blade is added to the chassis.